There are many sports that make money on their players. But players can use Instagram to help them increase their marketing. By having pictures of themselves taken during games and practice they can increase interest in themselves at contract signing time. Or they might get more money when they had an endorsement from a company.
Athletes would do good to open up the link here to Instafollowers.co and see if this would help them to increase their popularity. If they want to get their name and image out there then Instagram would be very helpful. If they only have a few dozen followers that would not look good. They need to have good content but if they used this site to give them a few hundreds followers that might give them some more support later on.